1. Field of the Invention
The present invention relates to an organosiloxane compound and an organic light-emitting device including the same, and more particularly, to an organosiloxane compound having high solubility and high thermal stability constituting a film having high thermal stability, and an organic light-emitting device having a low operating voltage, high efficiency, and high color purity including the organosiloxane compound.
2. Description of the Related Art
Light-emitting devices are self-emission type devices and have wide viewing angles, excellent contrast, and short response times. Organic light-emitting devices can be categorized into inorganic light-emitting devices having emitting layers formed of inorganic compounds and organic light-emitting devices (OLEDs) having emitting layers formed of organic compounds. OLEDs have high brightness, low operating voltages, and short response times, and can realize various colors, compared to inorganic light-emitting devices. As a result, a lot of research into OLEDs is being conducted.
In general, an OLED has an anode/organic emitting layer/cathode structure. However, an OLED can have various structures, such as an anode/hole injection layer/hole transport layer/emitting layer/electron transport layer/electron injection layer/cathode structure, an anode/hole injection layer/hole transport layer/emitting layer/hole blocking layer/electron transport layer/electron injection layer/cathode structure, or the like.
Materials used to manufacture OLEDs can be categorized into vacuum deposition materials and solution coating materials, according to a method of forming an organic layer. A vacuum deposition material should have a vapor pressure of 10−6 torr or higher, and can be a small molecular material having a molecular weight of 1200 or less. A solution coating material should have high solubility with respect to a solvent such that it can be prepared in a liquid state, and can be aromatic or polycyclic material.
When an OLED is manufactured using a vacuum deposition method, a vacuum system is required and thus manufacturing costs increase, and when a shadow mask is used to define a pixel used for displaying natural color, it is difficult to obtain a pixel having high resolution. On the other hand, a solution coating method, such as an inkjet printing method, a screen printing method, or a spin coating method, can be easily used, is inexpensive, and can be used to obtain a relatively higher pixel resolution than when a shadow mask is used.
However, among materials that can be used in a solution coating method, blue light-emitting molecules exhibit inferior thermal stability and color purity compared to materials that can be used in a vacuum deposition method. In addition, even when blue light-emitting molecules have high thermal stability and high color purity are used, an organic layer formed of the blue light-emitting molecules is gradually crystallized such that visible rays are dispersed, a whitening effect takes place, and pinholes can be formed, since the size of the formed crystals corresponds to a wavelength of visible light. Thus a device may easily deteriorate.
For example, U.S. Pat. No. 4,672,265 discloses a compound having π electron system susceptible to external perturbation and can be excited by electric field. However, the compound exhibits low heat resistance stability. U.S. Pat. No. 6,307,083 discloses specific organic silane compounds. The specific organic silane compounds have high solubility with respect to a solvent but a film formed of the organic silane compound using a solution coating method exhibits bad film quality and an organic light-emitting device including the film formed of the organic silane compound exhibits inferior performance.
Accordingly, there is a need to develop an organic light-emitting device having a low operating voltage, high brightness, high efficiency, and high color purity using a blue light-emitting compound having good thermal stability constituting an organic layer having good film quality.